Device for repairing tire punctures

ABSTRACT

A repair device for sealing a puncture hole in a tire includes a plug made of rubber which is shaped to make a snug fit into the hole. When heated, the plug fuses to the tire casing.

O Umted States Patent 1191 1111 3,773,097 Mullins Nov. 20, 1973 [54]DEVICE FOR REPAIRING TIRE 3,382,907 5 1968 Hough 152 361 PUNCTURES2,974,715 3/1961 Soares et al. 154/14 3,296,048 1/1967 Wolfe 156 97Inventor: GeneM-Mull1ns,M0nr0v1a,Ca11f- 2,966,189 12/1960 Chambers et31.. ..152/370 3,088,512 5/1963 Buckland.... 152 370 [73] Asslgnee' E aFwhltmoresan Manno 3,267,982 8 1966 Garrison 152/370 [22] Filed. Apr 211971 FOREIGN PATENTS OR APPLICATIONS 160,359 3/1920 Great Britain 152370 [21] Appl. No.2 136,270

Related US. Application Data Continuation of Ser. No. 805,179, March 7,1969, abandoned, which is a continuation-in-part of Ser. No. 713,454,March 15, 1968, abandoned.

Primary ExaminerGerald M Forlenza Assistant ExaminerRobert SaiferAttorney-Christie, Parker & Hale [5 7 ABSTRACT A repair device forsealing a puncture hole in a tire includes a plug made of rubber whichis shaped to make a snug fit into the hole. When heated, the plug fusesto the tire casing.

3 Claims, 8 Drawing Figures iliilliimlllllil Patented Nov. 20, 1973 2Sheets-Sheet 2 DEVICE FOR REPAIRING TIRE PUNCTURES REFERENCE TO RELATEDAPPLICATION This application is a continuation of application Ser. No.805,179, filed Mar. 7, 1969, now abandoned which is acontinuation-in-part of application Ser. No. 713,454, filed Mar. 15,1968 and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a device forsealing holes in resilient-walled objects designed to hold fluids orgases, especially when under pressure. More particularly, such device isused to repair puncture holes in vehicle tires having relatively thick,resilient walls such as truck, tractor, and bus tires.

A widely employed method for repairing punctures in truck tires,referred to as sectioning, involves beveling the puncture hole down tothe casing, positioning uncured rubber strips (sections) within theenlarged hole, and subjecting the rubber strips to heat and pressure. Anuncured rubber boot is also usually placed in the casing over thepuncture area, so that the cured strips and boot seal the hole. Althoughthis method results in an adherent seal, the time and skill required toproperly place the rubber strips in the puncture hole make it anexpensive, and often impractical repair process. Moreover, air is oftentrapped between the rubber layers, which occasions frequent tirefailure. The sectioning process also results in a weighty seal, due tothe enlargement of the hole and introduction therein of a significantnumber of the strips. The rubber strips are usually softer than theoriginal tread rubber, thus providing inferior wearing ability.

In an attempt to avoid the time and expense involved in the sectioningrepair method, cold patch techniques, i.e., those which do not requireheat and pressure, have been employed. ne such technique utilizes arubber plug attached to a boot for combined inside and outside repair ofa puncture, comparable to the use of the rubber strips and boot in thesectioning process. Special and often costly chemically bonding cementis used to bond the plug and boot to the tire. Despite a shorter timeperiod for application gained by use of this technique, carefulinstallation must still be made to obtain an adherent seal.

For example, in the process of enlarging the puncture hole for insertionof the plug, drilling usually must be done from .the inside of thecasing to obtain the required close seating of the plug at its base.This awkward step must also be accomplished without in any way burningor otherwise damaging the sides of the hole or disturbing the cordstherein so that a hole is formed which will closely mate with the plug.It is usually further required that a hole be drilled in the casing andenlarged to taper to a larger diameter from the inside to the outside ofthe tire. Even with a close fit, the chemically bonded plug is not asadherent or durable as the section repair. Moreover, the plug usuallyprotrudes, often by as much as one-half inch, above the tread and thusdoes not move in unison therewith. Thus, such cold patch is at best astopgap repair device, used when not enough time is available forsectioning or when a worn tire is not worth the expense of sectionrepair.

STATEMENT OF THE INVENTION The tire repair device of this inventionincludes a plug for insertion into the puncture hole from inside thetire. The plug makes a snug fit in the hole and is made of rubber whichis deformable, and curable to a resilient state wherein the plug fuseswith and becomes an integral part of the tire. Preferably, the plug isformed of uncured or partially cured rubber, usually natural rubber,although synthetic rubber of a deformable cured rubber plug can be usedas long as it has the property of being fusable to the tire. If the plugis made of substantially fully cured rubber, then a sheet of raw(uncured) or partially cured rubber is disposed around the more fullycured plug. When the plug is placed in the tire hole and heated, thesheet softens, fuses the plug to the tire, and cures to make a strongbond between the plug and tire.

Raw (or uncured) rubber softens when heated, stiffens when cooled, andhas low tensile strength and other unsatisfactory physical properties.It is improved by vulcanization, i.e., heating in the presence ofsulfur. vulcanization is a progressive reaction. It is preferablycarried to a point which produces a cured rubber with optimumproperties. Rubber which has not been heated long enough is undercured," while rubber which has been heated too long becomes charred, andis over cured.

Substantially raw or uncured rubber is herein defined as any solidrubber composition, whether natural or synthetic, which is sufficientlysimilar to raw rubber that it can be readily deformed and fused to thetire casing such that a firm, continuous bond is formed thereto.

Partially cured rubber is herein defined as any solid rubbercomposition, natural or synthetic, which is cured to a state wherein ithas sufficient strength and resilience to be forced into a puncture holewithout significantly being permanently deformed, and yet which 7 can atleast slightly soften and deform during curing to adapt to the contourof the puncture hole and fuse with the casing.

Curable rubber is used herein to mean either raw or partially curedrubber which will soften and fuse on heating.

Cured rubber is herein defined as that rubber which is vulcanized ortreated with heat or chemicals such that it does not melt with furtherheating.

A preferred tire repair device of this invention includes a pullingmember embedded in the plug. The pulling member has a higher tensilestrength than the plug, and facilitates pulling the plug into thepuncture hole in the tire. Preferably, a boot of curable rubber isattached to one end of the plug, and a shoulder of curable rubber isdisposed around the plug adjacent the boot member. The shoulder flowsreadily during curing and forms a head or flange on the inside of thetire and larger than the puncture to seal and lock the plug in place.Alternatively, the boot can be a separate piece that is bonded to theplug when the plug is sealed in the tire.

The repair device is installed by enlarging the puncture hole to removesubstantially all of the severed or ruptured parts of the tire, cleaningthe casing surface in the area of the puncture hole, inserting thepulling member into the hole from the inside of the tire to seat theplug in the hole, and applying heat and pressure to the tire to providea resilient, adherent seal of the puncture. Cementing and lubricatingfluid are usually applied to the hole and puncture area of the casing topermit ready insertion of the plug member and to obtain partial sealingof the boot member to the casing prior to the curing step. The strongpulling member makes it possible to pull the plug with great force intoa tight hole. This insures a strong bond between the plug and tire afterfusing under heat and pressure.

An important advantage results from the uncured rubber shoulder at thebase of the attached end of the plug because the shoulder flows readilyduring curing. After insertion of the plug in the puncture hole, andapplication of heat and pressure, the shoulder material rapidlyliquefies, allowing the adjacent portion of the plug to deformoutwardly, thereby providing a rivettype head on the casing side of thepuncture hole and driving the ready-flowing shoulder material fluid inits path. When the plug is attached to a boot, the shoulder compositionfills and seals the space between the casing and boot resulting fromprotrusion of the plug. When an uncured natural rubber boot is employedwith a semi-cured plug and uncured natural rubber shoulder, the curedassembly is characterized by a continuous, adherent and durable,integral seal which responds in unison with the tire tread to forcesexerted on the tire.

Although the utilization of a shoulder at the base of the plug is anespecially preferred embodiment of this invention, the device withoutsuch shoulder feature can also be employed as noted above. The simplerdevice is ordinarily employed only to repair small diameter punctures,i.e., those below about of an inch, the preferred form being almostexclusively used with larger diameter punctures.

The repair device is characterized by an ease of application comparableto that gained using the cold patch technique, yet affords a moredurable seal. That is, relatively little skill or time is required forinstalling the repair device of this invention, in contrast with themuch more demanding hand technique required by the sectioning process.Instead of carefully preparing a beveled opening and positioning thereina number of layers of rubber strips, the worker need only drill a hole,insert the plug, and cure in a heat and pressure mold.

Curing of the repair device within the puncture hole can be accomplishedusing conventional section or retread molding equipment, usuallyincluding a mandrel or air bag, female mold, and heating element.Because of the significantly lesser amount of sealing materials used,however, and due to the use of a semi-cured plug, the time required forthe molding operation is considerably less than that required forsectioning. Curing of the plug, shoulder and boot, when an uncuredrubber boot is employed, can often be accomplished in onethird the time,or less, normally required in sectioning.

In addition to allowing a shorter molding period, the repair device ofthis invention requires less time for installation prior to curing ofthe parts. That is, painstaking preparation of the puncture hole, asnoted above, is not necessary. After determining the direction of thepuncture by probing with a metal rod, the puncture hole is quicklydrilled from the outside surface of the tire. Thus, besides requiringless skill for installation, the overall time required is considerablyless than that necessitated by sectioning. Consequently, the repairdevice can be applied at a much lower cost.

The repair device also provides a more durable puncture seal than thesection because of the minimal hole enlargement required using suchdevice. That is, a

puncture hole need by drilled only to such diameter to include thepuncture, and not further. The section technique requires abevel-cutting procedure which removes significantly more of the tiretread, often requiring regrooving of the tire tread, which is almostnever called for when employing the subject repair device. Obviously,the more original undamaged tread which remains, the stronger therepair. Additionally, as mentioned above, the use of a smaller quantityof repair device materials results in a lighter weight seal and thus aless costly and less troublesome seal.

Installation of the device before curing is also simpler than thatcharacteristic of the cold patch process where concern is necessary toeffect a close fit of the plug in the puncture hole. This requirementusually calls for drilling from within the casing, an awkward procedurewhich often leads to inaccurate drilling, i.e., the puncture path ismissed by the drill. Using the repair device of this invention,considerations of this type are not necessary, since there need only beformed a puncture hole for the simple role of accepting the plug, thebonding of the elements being accomplished by application of heat andpressure. Although the subject repair device normally requires a longeroverall time for installation than does the cold patch method, the finalrepair occasioned by use of such novel device is much more durable,therefore providing a far superior tire repair.

In addition to repairing tread punctures, the repair device can also beapplied to punctures on the shoulder, side walls, and near the bead oftires, whereas cold patch devices have generally been restricted topunctures in or near the tire tread. Even punctures which angle throughthe tire tread can be repaired using the subject repair device becauseof the unique combination of components utilized.

Since the tire repair device of this invention can be easily installedin minimum time to provide a more durable, lightweight and low-cost sealof tire punctures, it is especially advantageous for repairing trucktires or similar large and costly tires which are more economical torepair and often recap than to replace with new tires. Off-the-roadtractor or equipment tires are also well suited for such repair. Repairof any punctured resilient walls, however, can also take advantage ofthe properties of the invention.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the tirerepair device of this invention.

FIGS. 2, 3 and 4 show the steps in making the tire repair device.

FIG. 5 is a sectional elevation of the presently preferred embodiment.

FIG. 6 is a view of the tire repair device in position to be installedin a puncture hole in a tire.

FIG. 7 is a sectional view of the tire repair device of FIG. 6 afterinsertion of the plug and prior to curing.

FIG. 8 is a sectional view showing the tire repair device after curingwith heat and pressure.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIG. 1, a semicuredrubber plug 10 includes an elongated cylindrical body 11 with a nose 12in the form of a truncated cone bonded at its larger end to one end ofthe body 1 1. An eyebolt 14 is embedded in the cone as described morefully below. An uncured rubber boot 16 in the fOl'lTl of a flat sheet issecured to the end of the plug opposite the cone. Four radiallyextending cords or strings 17 are bonded between the boot and plug toextend outwardly over the surface of the boot and provide escape pathsfor air during the curing operation described below.

Referring to FIGS. 2, 3 and 4, the tire repair device of FIG. 1 is madeby wrapping a threaded pilot bolt 18 in a trapezoidal sheet 20 offibreglass matting in an identically shaped sheet 21 of raw rubber. Thesheets 20 and 21 each have parallel edges 23 and 24 at their respectivetops and bottoms, and upwardly and inwardly sloping sides 26 so thatwhen the pilot bolt and a nut 27 threaded on the pilot bolt adjacent itslower end are wrapped in the two sheets, a spiralled cone 28 offibreglass matting and raw rubber is formed around the bolt and nut. Thelarger end of the spiralled cone is bonded with rubber cement to one endof the cylindrical body 11. The upper end 29 of the pilot bolt extendsfrom the narrow end of the cone and is square in cross section. Thecone, cylinder, bolt and nut are placed in a mold 30 which has a cavity31 shaped to receive the end of the bolt projecting from the smaller endof the spiralled cone, the cone itself and the cylinder 11. Preferablythe cylinder is of uncured or semicured rubber, which can be eitherextruded or rolled rubber sheet. An elongated core 32 of rubber harderthan that of the cylinder lies on the longitudinal axis of the cylinder.Preferably the core is square or diamond shaped in cross section and isthe same length as the cylinder, with one end of the core adjacent thebase of the cone and the other end just inside the cylinder. As shownbest in FIG. 5, the wall thickness of the annular body 11 issubstantially greater than the corresponding transverse dimension of thecore.

Pressure is applied to the material in the mold by a piston 33, and themold is heated to between 200 F and 300 F. The raw rubber and partiallycured rubber softens and becomes fluid so that it completely fills themold. A portion of the rubber in the spiralled cone flows over theexposed end of the pilot bolt and coats it. The sheet of raw rubber inthe spiralled cone fuses together and permeates the fibreglass mattingso that the two materials form an integral reinforcing structure aroundthe pilot bolt and nut. The cone is also integrally fused with thecylinder. The rubber in the cylindrical part of the plug can either becompletely cured or only partially cured. In either case, asubstantially monolithic structure is formed.

The mold is cooled and the plug is removed from it. The rubber aroundthe exposed end of the pilot bolt is cut away and the exposed end isrotated to back it out of the nut and a threaded bore 34 formed by thepresence of the pilot bolt in the cone.

Whether the cylinder 11 is completely or only partially cured, it ispreferable to bond a strip 35 of raw or partially cured rubber aroundthe end of the cylinder 11 opposite the cone to form an annular shoulder36. The strip 35 is secured to the cylinder 1 1 by dipping the cylinderin a liquid rubber cement, which is a solution of liquid rubber or rawrubber dissolved in a solvent, to make the cylinder tacky. Thereafter,the strip 35 is wrapped around the cylinder and bonded to it by theliquid rubber cement. It is also preferred to cement a sleeve 38 of rawrubber around the cylinder and strip to facilitate bonding the plug tothe tire under repair as described below. If desired, the boot 16(FIG. 1) can be added at this time or the plug can be used without theboot. The strip 35 can be applied first as shown in FIG. 5 or it can beapplied after sleeve 38.

Referring to FIGS. 6-8, when the plug is ready to be used to repair ahole 40 in a tire 41, eyebolt 14 is threaded into the bore 34 and nut27, and the tapered end of the plug is placed in the hole from theinside of the tire so that the eyebolt projects through the hole. Asuitable lever (not shown) or other device is passed through the eyeboltso that the plug can be pulled with a substantially larger force thanwould be possible if the eyebolt were not present. The nut andfibreglass embedded in the cone around the bolt shank provide a strongand large area of contact with the cylindrical portion of the plug so itcan be deformed and firmly forced to make a snug fit in the hole.

The outer coating or sleeve of uncured rubber prevents the strip whichforms the shoulder from being peeled off during storage or installation.

The plug and boot are now in the position shown in FIG. 7, i.e.,shoulder 36 bears against the inside surface of the tire.

At this precuring stage, it is especially preferred that a cement oradhesive composition be employed between the casing and boot topenetrate the fabric and rubber of the tire and hold the boot in theillustrated seating position. Any conventional rubber adhesive or cementcomposition is usable. Thus, a layer of such adhesive composition ispreferably applied to the casing before insertion of the repair deviceinto the puncture hole, and the boot is then stitched, or rolled intoadhesive contact therewith, using conventional stitching tools.

The eyebolt is unscrewed and removed from the plug, which is then cut asshown in FIG. 7, to leave a small portion of the cylinder projectingbeyond the outside surface of the tire.

Heat and pressure are applied by conventional tire mold to cause thesleeve and shoulder to melt, cure, and fuse the plug and casingtogether. The shoulder spreads to the position as shown in FIG. 8 toform an outwardly extending flange or rivet head 43 which fills thespace between the boot and tire and creates an;integral bond betweenthem. If the rubber in the plug cylinder is not already completelycured, the curing is finished during the molding operation.

During the molding operation in the tire mold, the strings (shown onlyin FIG. 1) provide escape paths for air and gas and thereby prevent theformation of trapped bubbles which would weaken the repair job.

As shown by FIG. 7, seating occurs when the casing rests upon theshoulder, which has a smooth or beveled outer edge. This particulardesign most readily allows the shoulder material to flow during curing,outwardly from the plug so that the plug can be formed in the desiredmanner. Other shoulder designs, such as those utilizing angular edges ornoncontinuous edges or sides, can also be employed as long as theypermit the described deformation of the plug. The preferred smoothtypeshoulder, however, accomplishes this purpose without requiring carefulattenuation to seating of the plug.

Referring to FIG. 8, the plug has been deformed under heat and pressureto provide a rivet-type head which, together with bonding of the treadrubber with the rubber plug, forms an adherent and durable seal of thepuncture hole. The shoulder and sleeve (FIG. 5) have been completelyliquefied, the uncured rubber being forced away from the plug during itsdeformation and being cured as a layer where it aids in further securingthe repair device. Any molding equipment or suitable apparatus can beemployed to cure the repair device under pressure. Using conventionalpressures and temperatures, the time required is usually about one-thirdof that required for a corresponding section repair. After curing, outerplug protrusions, if present, are buffed or otherwise removed, exposingthe core of harder rubber in the center of the plug. The tire is nowready for use.

The annular body of rubber in the cylindrical portion of the plug has aDurorneter hardness of between about 30 and about 40, and the harderrubber of the core has a Durorneter hardness between about 50 and about60. Thus, the core is of harder and tougher rubber so it resists wearbetter than the surrounding portion of the plug. This facilitates longerwear of the plug and prevents dishing" or concave wearing of the plugduring the subsequent use of the tire.

Often, the repair devices of this invention are utilized on tires to berecapped but such repair devices are equally valuable simply forrepairing tires which are to be directly reused, without being recapped.

The boot employed in the repair device of this invention as noted abovepreferably is attached to the plug before installation, although itcould be attached during or subsequent to curing and deformation of theplug. The boot material also preferably comprises uncured naturalrubber, although semicured and even cured rubber boots can be employedin repair devices constructed with the shoulder member. When a devicewithout such shoulder is utilized, however, it is essential that theboot composition be substantially uncured, as discussed above.Additionally, the boot usually consists of a number of overlappinglayers of uncured rubber having cords disposed therein for furtherincreasing the strength of the repair. Ordinarily the boot is of arectangular or oval shape having a thickness of up to about 9% inch, theplug being attached at its center.

Preferably the shoulder material comprises an uncured natural rubbercomposition characterized by fast flowing properties during curing,although any compositions having similar properties, such aslike-behaving natural or synthetic rubber compositions, can also beemployed. The dimension of the shoulder material depends mainly upon thesize of the plug used and thus varies with the size of the puncturehole. Generally, the shoulder has a height of up to about h inch and athickness of up to about A inch.

The plug material preferably is a semicured natural rubber or a similarcurable and deformable material which can be used as a sealing device inaccordance with this invention. It is desirable that the plug be atleast partially uncured because it can be finally cured to provide theadherency characteristic of the disclosed repair device. If the plug isfully cured before use, the raw rubber sleeve effects a strong bond.

The preferred natural rubber for use in making the shoulder material andthe boot comprises cis-l ,4- polyisoprene, a stereo-specific polymerproduced by natural growth processes in rubber trees and plants.Modifications of this polymer as well as synthetic rubbers, such asstyrene-butadiene rubber, acrylonitrile rubber, and the like, andsynthetic natural rubbers,

such as cispolybutadiene and cis-polyisoprene, are also suitable whenformulated or modified such as to function as described.

in carrying out the process of this invention, a hole is first drilledaround the tire rupture or puncture, the direction of the puncture beingdetermined by insertion of a rod therein. A hollow drill bit is thenused for the drilling. A small diameter bit is first used, followed by alarger one, until a smooth ring of tire is removed, the smooth ringindicating that no broken or ruptured cords lie outside of the hole. Theinside of the tire casing in the area of the puncture is then buffed orotherwise cleaned to remove dirt and moisture. The puncture area isusually roughened to insure adhesion. A cement coating,-which mayconsist of any conventional vulcanizing composition, is then ordinarilyapplied to the buffed area and dried over about a 30 minute period. Theunattached end of the plug is then inserted into the hole, grasped fromthe outside of the tire and pulled into seating position. The protrudingportion of the plug is cut off above the tread level, preferably aboutone-quarter to l inch above the tread level, and the tire is placed in amold for curing. As noted above, conventional section molding equipmentor any suitable apparatus can be so employed. After a curing stage ofabout one hour, the tire can be removed.

The described tire repair device can be used with tires having tubes, aswell as with tubeless tires, to seal puncture holes of diameters up toabout four inches and greater. It is noted, however, that this inventioncan be used to repair holes in any wall of relatively resistantmaterial, and reference to a tire repair device is not to be consideredlimiting to tire repair applications.

I claim:

1. A device for repairing a hole in a tire, the device comprising arubber plug of a size and shape to make a snug fit within the hole, anut embedded in the plug, an elongated bolt threaded into the nut andembedded in the plug, the bolt extending from the plug to facilitatepulling the plug into the hole, and a reinforcing material embedded inthe plug and surrounding the bolt and the nut, the bolt having a highertensile strength than the plug.

2. A repair device according to claim 1 in which the bolt is an eyeboltwith the eye portion of the bolt projecting from the plug.

3. A device for repairing a hole in a tire, the device comprising anelongated rubber plug of a size and shape to make a snug fit within thehole, the plug including an elongated core of cured rubber, an annularbody of cured rubber having a hardness less than that of the core, thecore and annular body being fused together to form a substantiallymonolithic plug, the annular body having a wall thickness greater thanthe corresponding transverse dimension of the core, an external annularshoulder of curable rubber secured around and adjacent one end of theplug, a boot of curable rubber bonded to the end of the plug andadjacent the shoulder of cured rubber, and string bonded between theboot and the plug, the string extending from the portion of the bootbonded to the plug to the periphery of the boot to provide an escape forair when the boot and annular shoulder are heated to bond them and theplug to the tire.

1. A device for repairing a hole in a tire, the device comprising arubber plug of a size and shape to make a snug fit within the hole, anut embedded in the plug, an elongated bolt threaded into the nut andembedded in the plug, the bolt extending from the plug to facilitatepulling the plug into the hole, and a reinforcing material embedded inthe plug and surrounding the bolt and the nut, the bolt having a highertensile strength than the plug.
 2. A repair device according to claim 1in which the bolt is an eyebolt with the eye portion of the boltprojecting from the plug.
 3. A device for repairing a hole in a tire,the device comprising an elongated rubber plug of a size and shape tomake a snug fit within the hole, the plug including an elongated core ofcured rubber, an annular body of cured rubber having a hardness lessthan that of the core, the core and annular body being fused together toform a substantially monolithic plug, the annular body having a wallthickness greater than the corresponding transverse dimension of thecore, an external annular shoulder of cuRable rubber secured around andadjacent one end of the plug, a boot of curable rubber bonded to the endof the plug and adjacent the shoulder of cured rubber, and string bondedbetween the boot and the plug, the string extending from the portion ofthe boot bonded to the plug to the periphery of the boot to provide anescape for air when the boot and annular shoulder are heated to bondthem and the plug to the tire.